[SI-LIST] Re: Floating Cable Shield

  • From: Ivor Bowden <ivorlist@xxxxxxxxxxx>
  • To: Shawn Nikoukary <shawnn@xxxxxxxxxxx>
  • Date: Wed, 11 Oct 2006 10:06:56 -0700

Hi Shawn,

I don't have a camera here, but the cable had ID on it, so I looked it 
up on the web. If you go to:
and click on
Rounded Cable -> IDE
you can see an image. The cable I have is the clear one with the silver 
braid. The images aren't that big, but you can get an idea.

It doesn't make any sense to me, that's why I posted. If there is to be 
a shield on the cable, it should be well grounded at both ends, imo.


on 10/11/2006 8:38 AM PDT Shawn Nikoukary wrote:
> Hello Ivor,
> Is it possible for you to send us a pic or the link of manufacturer for
> this cable?  I am curious to see how it looks.
> Regards,
> Shawn Nikoukary               Cadence Design Systems
> Sales Technical Lead                  2655 Seely Ave, MS 9B2  
> Silicon Package Board Division        San Jose, CA 95134  
> Office (408) 944-7328                 Cell (408) 712-1073  
> Email: shawnn@xxxxxxxxxxx     Fax (408) 944-7772
> -----Original Message-----
> From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
> On Behalf Of Ivor Bowden
> Sent: Wednesday, October 11, 2006 8:29 AM
> To: si-list@xxxxxxxxxxxxx
> Subject: [SI-LIST] Floating Cable Shield
> Hi,
> I ran into what I thought was an interesting cable and am looking for 
> comments. This is an IDE cable on a new PC I got. The construction is 
> twisted pair ribbon cable (flat spots for IDCs between the twisted 
> sections), about 20" long, IDC both ends, a 3rd IDC about 7" from one 
> end. What makes the cable interesting to me is there are two braided 
> shields covering the bundled twisted pair sections, one about 8", the 
> other about 3.5". These shields have no connections, not to a drain 
> wire, not to each other and to to any circuit or frame ground, they are 
> entirely floating. My question is, how effective is this type of 
> "floating" shield, in terms of SI and EMI?
> This also brings up the general question of cable shield termination, 
> circuit/chassis ground at both ends v.s. one end only v.s. floating; 
> what characteristics to expect in each case?
> And that brings up the specific question of shield return treatment in 
> the connector area, single drain wire v.s. complete enclosure?
> Thanks,
> Ivor Bowden
> Hardware Engineer
> Curtiss-Wright Controls Embedded Computing
> Video and Graphics
> San Diego, CA 92121

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